This invention relates to a method for preparing hydroxyalkyl-functionalized polyphenylene ether which is obtained by functionalizing of the terminal phenolic hydroxyl group of a polyphenylene ether.
More specifically, the hydroxyalkyl-functionalized polyphenylene ether according to the method of the present invention can be considered to have effects, when blended with the other resin, etc., of heightening solubility between resins by reacting with functional groups of a resin to be blended and increasing strength of a composition as compared with a non-functionalized polyphenylene ether resin. Further, it is available for a precursor of a graft or block copolymer.
A polyphenylene ether resin is an extremely available thermoplastic resin having excellent heat resistance, mechanical characteristics, electric characteristics, water resistance, acid resistance, alkali resistance and self-extinguishing properties. Thus, it has been planning to use for many applications as an engineering plastic material. However, this resin has high melt viscosity which relates to high glass transition temperature, and thus, poor in molding property. Further, it has a disadvantage that impact resistance is poor as an engineering plastic.
In order to solve these problems, a polyolefin or an engineering plastic is blended with the polyphenylene ether, but the polyphenylene ether is essentially poor in compatibility with these polymers. Also, the resulting composition is weak and lowered in mechanical strength and impact strength whereby such a composition cannot be practically used. For solving the problem, a compatibilizing agent has been used, but many of the compatibilizing agents are a graft or block copolymer of the both polymers. When these copolymers are to be synthesized, a terminal phenolic hydroxyl group of the polyphenylene ether resin can be considered to react with a functional group in the other polymer.
However, the kinds of functional groups of the other polymers capable of reacting with the terminal phenolic hydroxyl group are limited so that utilizable range is restricted naturally. Thus, many functionalized polyphenylene ethers have been proposed in order to heighten reactivity of the polyphenylene ether resin. In Japanese Provisional Patent PCT Publications No. 500456/1987, No. 500803/1988 and No. 503391/1988, examples of some hydroxyalkyl group-functionalized polyphenylene ethers have been mentioned, but many steps of reactions are required for preparing the same and a melting reaction at a high temperature should be employed in many cases. Also, even when the modification can be carried out under relatively moderate reaction conditions, there is the problem that expensive acid chloride should necessarily be used. Further, in Japanese Provisional Patent Publication No. 128021/1988, there is disclosed a method in which a polyphenylene ether and ethylene oxide or propylene oxide are reacted to hydroxyalkylate the terminal of the polyphenylene ether. However, this method involves the problems that the reaction should be carried out under high pressure, control of an added number of ethylene oxide or propylene oxide is difficult and a uniform product can hardly be obtained.